1. Field of the Invention
The invention relates to a test method for estimating the affinity of a product for a target substance, more specifically by treating a substrate that is noticeably affected when contacted by the product with the target substance and assessing the affinity of the product for the target substance by observing any change in the substrate upon application of the product to the coated or otherwise treated substrate.
2. The Related Art
Various tests for comparison of attributes of products have been used. Such tests involve e.g. a comparison of the acidity or alkalinity of the product using litmus paper. Other tests involve comparison of selected physical and chemical properties of the products such, as speed of dissolution of tablets, degree of foaming of detergent compositions and similar visual methods. Surprisingly, it has been found that products may be effectively compared by comparing their affinity for a target substance coated onto or contacted with a sensitive substrate where the substrate will evidence a noticeable change upon contact with the product in the absence of the target substance.
Personal cleansing products are frequently marketed based on their degree of mildness to the skin of the user. Clinical data collected from measurements of skin dryness and erythema are often referred to when comparing different personal cleansing products. However, such comparisons are frequently not dramatic enough to catch the attention of the average person who is still interested in selecting a mild cleansing product for their cleansing needs. Surprisingly, it has been found that a substrate that is noticeably or measurably sensitive to such cleansing products, such as a fresh cut flower, may be advantageously used to convey differences in mildness of cleansing products when employed according the present invention.